Door construction



ug.15,19331. 'CQQJOHNSON ML 1,922,370

` DOOR CONSTRUCTION,-

Filed Aug.' 4. 1951` 2 sheets-sheet 1 l 2 gNvENTon A ATTORNEYS.`Aug.1s,1933.` c aJoHNsoNET AL 1;922,370

Doo CONSTRUCTION ATTORNEYS Patented Aug. `15, 1933 PATENT OFFICE D001!CONSTRUCTION Clarence G. Johnson and Herbert C.

Hartford City, Ind., assignors to Blodgett, Overhead Door Corporation,Hartford City, Ind., a Corporation of Indiana Application August 4,1931. sensi No. 555.108

The present lnventionpertains to a novel counterbalancing system forsliding doors particularly of the type wherein the door in opening movesfirst along a vertical track section and then onto a horizontal tracksection.

The principal object ofthe invention is to provide a device of thischaracter especially applicable to installations where the verticaltrack section extends a considerable distance over the topof the'dooropening, orin other words, where the clear space to the ceiling must beconsiderably higher than the door opening. A structure of this type may,for example, be a greasing station or repair shop where the automobileis lifted off the iioor.

In installations Where the vertical track section is substantially ashigh asl the door opening, the problem of counterbalancing the door iscomparativelyv simple, inasmuch as the effective, weight of the doorcommences to diminish immediately it is raised and the tension oi thecounterbalanced spring also commences to diminish at the same time.VHowever, in cases where the vertical track section is higher than thedoor opening, the door does not commence to lose its effective weightimmediately but only when it begins 'to ride on the horizontal tracksection, while the tension of the counterbalance spring on the otherhand begins to diminish immediately. f

The object of the invention, specifically, is to provide acounterbalancing system 'which meets this difilcultyor in other words,maintains a substantially constant relation between the counterbalancespring and the effective weight of the door at all times. This object isaccomplished generally by the use of cables wound on drums carried by aspring-tensioned shaft, the drums having a combination of conical andcylindrical portions so related that the effective radius oi' theconical portion varies while the door is entirely in the vertical tracksection, thereby compensating for the constantly changing tension of thespring although the unsupported weight of the door does not change.

A further object of the invention is to provide'a compensating devicewhich does away with the necessity of accurately winding the cables ontheir respective drums. Still another object is to provide safety meansto prevent dropping of the door under its own weight in the event thatthe counterbalance spring should break.

The invention is fully disclosed in the followingdescription, by way ofexample, and in the accompanying drawings in which- 1t) Claims. (Class20-20) 65 Reference to these views will now be had by use of likecharacters which are employed to designate corresponding partsthroughout.

A door frame l is built in any desired manner in a garage or otherstructure and presents a door opening 2 to be closed by a door of thehinged panel type. It will be seen that the building structure isconsiderably higher than the door opening.- A track consisting oi' apair oi rails is provided at the door opening, and each rail has asubstantially vertical portion 3 extending considerably above the dooropening and a substantially horizontal portion 4 extending rearwardly orinwardly from the upper end of the vertical portion. The door consistsof superimposed panels 5 joined together by hinges 6 on horizontal axes.The hinge pintles 7 carry rollers 8 riding in the tracks in the mannernow well known in the art.

In the opening oi' the door, the latter first rides completely on thevertical portions 3 luntil the upper panel moves onto the horizontalportion 4. Thus, the unsupported weight of the door remains constantuntil the door commences to ride on the horizontal portion 4, afterwhich the unsupported weight gradually diminishes. This type ofconstruction is suitable especially for buildingshaving a comparativelylarge height, as already indicated, and one example of such a structureis a garage or repair shop in which an automobileis lifted oil` theiloor forservice or repair work thereon. The height of the door opening2 is slightly greater than that of an automobile.

A shaft 10 for carrying a counterbalanclng means and cable drums for thedoor is rotatably supported in a convenient position, preferablydirectly over the door opening and parallel to the upper edge of thedoor, in bearings 11. The ends of the shaft carry drums, each having aconical portion 12 and a cylindrical portion 13 for a purpose which willpresently be described. The drums have cables 14 wound thereon,preferably in thread grooves 15 provided for the' purpose o! ensuringuniform winding and unwinding.

Each cable has its free end connected to a bracket 16 at the lowercorner of the door, preferably through the medium of a coil spring 17.To each bracket is secured a stop member 18 looped as at 19 around theadjacent cable and directly over the corresponding spring 17. The loopor eye 19 is of such size that the spring 17 cannot pass therethrough incase that it should break, so that the free end of the cable isnevertheless retained by the stop member if such breakage of the springshould occur. e

A torsional spring 20 surrounds the shaft 10 and has a plug 21 threadedinto one end thereof and keyed as at 22 to the shaft. The other end isfree of the shaft but has a similar plug 23 threaded therein andequipped with a stop finger 24 secured thereto by' bolts 25. Adjacentthis end of the spring, a bracket 26 is secured to the structure 1 andhas an arm 27 pivoted thereto by a stud 28. This arm is engaged by thestop nger 24 under the tension of the spring. It Will be seen that thearm 27 is of considerable length so that the finger may slide along thesame as the spring contracts or elongates on lowering or raising of thedoor. The spring may be adjustably tensioned for properlycounterbalancing the door by detaching the finger 24 and turning theplug 23 by a suitable tool inserted in apertures 29 formed in the plug.For the same l' purpose of adjustment, the finger 24 has av seriesv ofbolt holes 30 for connecting the finger 24 in various 'angular relationsto the plug.

The cables 14 are connected to the door in such a manner as towind rston the conical portions and then on the cylindrical portions as the l 20gradually loses its tension from the time the lifting movement iscommenced. During the initial lifting movement of the door, however, theeffective radius or leverage of each drum is diminished as the cablewinds towards the cylindrical portion. The conical portion of each drumis so dimensioned that the diminishing effective radius compensates thediminishing tension of the spring, whereby the spring main-i tains aproper counterbalancing relation to the door until the latter reachesthe horiontal portion 4 of the track.

As the door commences to ride on the horizontal portion of the track,its effective or unsupported weight gradually diminishes. It will alsobe recalled that the tension of the spring gradually diminishes.Consequently, the conical portion of each drum is constructed tofunction only until the door reaches the horizontal track section. Inother words, the cable-thread of each conical portion has a developedlength substantially equal to the difference between the height of thevertical track portion 3 and the height of the door. As the doorcommences to ride on the horizontal track section, the cables Wind onthe cylindrical parts of the drums, so

that there is no variation in the effective radii of the drums.' Thespring 20 is so constructed that it loses its tension in proportion tothe rate at which the door loses its effective or unsupported weight asit rides over the horizontal track section.

As the door is closed or lowered, it will be evident that theseconditions are relatively reversed, although the balancing action of thespring 20 'with respect to the unsupported weightl of the pawl has afork 34 straddling the arm 27 whereby the ratchet is normally held outof engagement with the pawl. A spring 35 tends to throw the pawl towardsthe ratchet but is resisted by the tension of the spring 20 acting onthe arm 27 through the medium of the nger 24. In the event that thespring 20 should break, the spring 35 is rendered free to throw the pawlinto engagement with the ratchet, although swinging the pivoted arm 27which is now unresisted. Thus, the door is prevented from dropping underits own weight in the event that the spring 20 breaks. The door is alsorendered safe against breakage of the spring 17 by the stops 18 and eye19 as previously described.

With reference again to the drums, it will be evident that the cablesmust ordinarily be accurately wound thereon, for otherwise one cablewould be on the conical portion while the other would be on thecylindrical portion, as a result of which oney cable would be fed orwound at a greater rate than the other cable, thereby tending to movethe ends of the door at different rates and consequently tilting thedoor to bind it in its track. The spring 17 however overcomes thenecessity for such accurate setting of the cables. Any unequal windingor feeding of the cables under the conditions described causes astretching of the spring 17 at the end of the door Which tends to bepulled upwardly with respect to the other end, whereby the effect of theunequal winding or unwinding is at least substantially overcome.

Although a specific embodiment of the invention has been illustrated anddescribed, it will be apparent that various alterations in the details`of construction may be made without departing from the scope of theinvention as indicated by the appended claims.

What We claim is:-

1. 4In combination with a vertically and horizontally slidable door, atrack guiding said door and having a vertical portion longer than theheight of the door and a substantially horizontal portion extending fromthe upper end of the vertical portion, a rotatable shaft, a torsionalspring surrounding said shaft and having one end secured to the shaft,stop means for the other end of said spring, a drum on said shaft havinga conical portion and a cylindrical portion, and a cable extending fromsaid drum and secured to said door and positioned to wind first on theconical portion and then on the cylindrical portion as the door israised.

2. In combination with a vertically and horizontally slidable door, atrack guiding said door and having a vertical portion longer than theheight of the door and a substantially horizontal portion extending fromthe upper and of the vertical portion, a rotatable shaft, a torsionalspring surrounding said shaft and having one end secured to the shaft,stop means for the other end of said spring, a drum on said shaft havinga conical portion and a cylindrical portion, and a cab e extending fromsaid drum and secured to said or and positioned to wind rst on theconical portion and then on the cylindrical portion as the door israised, said conical portion being so dimensioned that the cable andwind- 3. In combination with a vertically and horizontally slidabledoor, a track guiding said door and having a vertical portion longerthan the height of the door and a substantially horizontal portionextending from the upper end of the vertical portion, a rotatable shaft,a torsional spring surrounding said shaft and having one end secured tothe shaft, stop means for the other end of said spring, a drum on saidshaft having a conical portion and a cylindrical portion, and a cableextending from said drum and secured to said door and positioned to Windfirst on the conical portion and then on the cylindrical portion as thedoor is raised, the cable-thread on the conical portion having adeveloped length substantially equal to the difference between thelength of the vertical portion of the track and the height of said door.

4. In combination with a vertically and horizontally slidable door, atrack guiding said door and having a vertical portion longer than theheight of the door and a substantially horizontal portion extending fromthe upper end of the vertical portion, a rotatable shaft, a torsionalspring surrounding said shaft and having one end secured to the shaft,stop means for the other Yend of said spring, a drum on said shafthaving a conical portion and a cylindrical portion at the smaller end ofthe conical portion, and a cable extending from saiddrum and seciired tosaid door and positioned to wind rst on the conical portion and then onthe cylindrical portion as the door is raised.

5. In combination with a vertically and horizontally slidable door, atrack guiding said door and having a vertical portion longer than theheight of the door and a substantially horizontal portion extending fromthe upper end of the vertical portion, a rotatable shaft, a torsionalspring surrounding said shaft and having one end secured to the shaft,stop means for the other end of said spring, a drum on said shaft havinga conical portion and a cylindrical portion at the smaller end of theconical portion, and a cable extending from said drum and secured tosaid door and positioned to wind rst on the conical portion and then onthe cylindrical portion as the door is raised, the cablethread on theconical portion 'having a developed length substantially equal to thedifference between the length of the vertical portion of the track andthe height of said door.

6. In combination with a vertically slidable door, a shaft parallel tothe upper edge of said door, a single counterbalance means acting onsaid shaft, drums on the ends of said shaft, cables wound on said drumsand connected to said door, and springs inserted in said cables.

7. In combination with a vertically slidable door, a shaft parallel tothe upper edge of said door, a single counterbalance means acting onsaid shaft, drums on the ends of said shaft, cables wound on said drums,springs connecting said cables to said door and stop members carried bysaid door and having eyes looped around said cables adjacent saidsprings, said springs being too large to pass through said eyes.

8. In combination with a vertically slidable door, a shaft parallel tothe upper edge of said door, a counterbalance torsional spring havingone end secured to said shaftan arm pivotally mounted adjacent saidtorsional spring, a nger extending from the remaining end of said springand engaging said arm under spring tension, a ratchet on said shaft, apawl pivotally mounted adjacent said ratchet and held by said arm awayfrom said'ratchet, and means tending to throw said pawl into engagementwith said ratchet and operative on release of said arm by breaking ofsaid spring.

9. In combination with a vertically slidable door, a shaft parallel tothe upper edge of said door, a counterbalance torsional spring havingone end secured to said shaft, an arm pivotally mounted adjacent saidtorsional spring, a stop iinge'r secured to the remaining end of saidspring for angular adjustment relatively thereto and engageable withsaid arm, a ratchet on said shaft, a pawl pivotally mounted adjacentsaid ratchet and held by said arm away from said ratchet, and

.means tending to throw said pawl into engage-

